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Memory with Postgres

This example demonstrates how to use Mastra's memory system with PostgreSQL as the storage backend.

Prerequisites​

This example uses the openai model and requires a PostgreSQL database with the pgvector extension. Make sure to add the following to your .env file:

.env
OPENAI_API_KEY=<your-api-key>
DATABASE_URL=<your-connection-string>

And install the following package:

npm install @mastra/pg

Adding memory to an agent​

To add PostgreSQL memory to an agent use the Memory class and create a new storage key using PostgresStore. The connectionString can either be a remote location, or a local database connection.

src/mastra/agents/example-pg-agent.ts
import { Memory } from "@mastra/memory";
import { Agent } from "@mastra/core/agent";
import { openai } from "@ai-sdk/openai";
import { PostgresStore } from "@mastra/pg";

export const pgAgent = new Agent({
  name: "pg-agent",
  instructions:
    "You are an AI agent with the ability to automatically recall memories from previous interactions.",
  model: openai("gpt-4o"),
  memory: new Memory({
    storage: new PostgresStore({
      connectionString: process.env.DATABASE_URL!,
    }),
    options: {
      generateTitle: true, // Explicitly enable automatic title generation
    },
  }),
});

Local embeddings with fastembed​

Embeddings are numeric vectors used by memory’s semanticRecall to retrieve related messages by meaning (not keywords). This setup uses @mastra/fastembed to generate vector embeddings.

Install fastembed to get started:

npm install @mastra/fastembed

Add the following to your agent:

src/mastra/agents/example-pg-agent.ts
import { Memory } from "@mastra/memory";
import { Agent } from "@mastra/core/agent";
import { openai } from "@ai-sdk/openai";
import { PostgresStore, PgVector } from "@mastra/pg";
import { fastembed } from "@mastra/fastembed";

export const pgAgent = new Agent({
  name: "pg-agent",
  instructions:
    "You are an AI agent with the ability to automatically recall memories from previous interactions.",
  model: openai("gpt-4o"),
  memory: new Memory({
    storage: new PostgresStore({
      connectionString: process.env.DATABASE_URL!,
    }),
    vector: new PgVector({
      connectionString: process.env.DATABASE_URL!,
    }),
    embedder: fastembed,
    options: {
      lastMessages: 10,
      semanticRecall: {
        topK: 3,
        messageRange: 2,
      },
    },
  }),
});

Usage example​

Use memoryOptions to scope recall for this request. Set lastMessages: 5 to limit recency-based recall, and use semanticRecall to fetch the topK: 3 most relevant messages, including messageRange: 2 neighboring messages for context around each match.

src/test-pg-agent.ts
import "dotenv/config";

import { mastra } from "./mastra";

const threadId = "123";
const resourceId = "user-456";

const agent = mastra.getAgent("pgAgent");

const message = await agent.stream("My name is Mastra", {
  memory: {
    thread: threadId,
    resource: resourceId,
  },
});

await message.textStream.pipeTo(new WritableStream());

const stream = await agent.stream("What's my name?", {
  memory: {
    thread: threadId,
    resource: resourceId,
  },
  memoryOptions: {
    lastMessages: 5,
    semanticRecall: {
      topK: 3,
      messageRange: 2,
    },
  },
});

for await (const chunk of stream.textStream) {
  process.stdout.write(chunk);
}

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